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8#include <linux/memory.h>
9#include <linux/uaccess.h>
10#include <linux/module.h>
11#include <linux/list.h>
12#include <linux/slab.h>
13#include <linux/sort.h>
14#include <linux/err.h>
15#include <linux/static_key.h>
16#include <linux/jump_label_ratelimit.h>
17#include <linux/bug.h>
18
19#ifdef HAVE_JUMP_LABEL
20
21
22static DEFINE_MUTEX(jump_label_mutex);
23
24void jump_label_lock(void)
25{
26 mutex_lock(&jump_label_mutex);
27}
28
29void jump_label_unlock(void)
30{
31 mutex_unlock(&jump_label_mutex);
32}
33
34static int jump_label_cmp(const void *a, const void *b)
35{
36 const struct jump_entry *jea = a;
37 const struct jump_entry *jeb = b;
38
39 if (jea->key < jeb->key)
40 return -1;
41
42 if (jea->key > jeb->key)
43 return 1;
44
45 return 0;
46}
47
48static void
49jump_label_sort_entries(struct jump_entry *start, struct jump_entry *stop)
50{
51 unsigned long size;
52
53 size = (((unsigned long)stop - (unsigned long)start)
54 / sizeof(struct jump_entry));
55 sort(start, size, sizeof(struct jump_entry), jump_label_cmp, NULL);
56}
57
58static void jump_label_update(struct static_key *key);
59
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66
67
68
69int static_key_count(struct static_key *key)
70{
71
72
73
74
75 int n = atomic_read(&key->enabled);
76
77 return n >= 0 ? n : 1;
78}
79EXPORT_SYMBOL_GPL(static_key_count);
80
81void static_key_enable(struct static_key *key)
82{
83 int count = static_key_count(key);
84
85 WARN_ON_ONCE(count < 0 || count > 1);
86
87 if (!count)
88 static_key_slow_inc(key);
89}
90EXPORT_SYMBOL_GPL(static_key_enable);
91
92void static_key_disable(struct static_key *key)
93{
94 int count = static_key_count(key);
95
96 WARN_ON_ONCE(count < 0 || count > 1);
97
98 if (count)
99 static_key_slow_dec(key);
100}
101EXPORT_SYMBOL_GPL(static_key_disable);
102
103void static_key_slow_inc(struct static_key *key)
104{
105 int v, v1;
106
107 STATIC_KEY_CHECK_USE();
108
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119
120
121 for (v = atomic_read(&key->enabled); v > 0; v = v1) {
122 v1 = atomic_cmpxchg(&key->enabled, v, v + 1);
123 if (likely(v1 == v))
124 return;
125 }
126
127 jump_label_lock();
128 if (atomic_read(&key->enabled) == 0) {
129 atomic_set(&key->enabled, -1);
130 jump_label_update(key);
131 atomic_set(&key->enabled, 1);
132 } else {
133 atomic_inc(&key->enabled);
134 }
135 jump_label_unlock();
136}
137EXPORT_SYMBOL_GPL(static_key_slow_inc);
138
139static void __static_key_slow_dec(struct static_key *key,
140 unsigned long rate_limit, struct delayed_work *work)
141{
142
143
144
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146
147
148
149 if (!atomic_dec_and_mutex_lock(&key->enabled, &jump_label_mutex)) {
150 WARN(atomic_read(&key->enabled) < 0,
151 "jump label: negative count!\n");
152 return;
153 }
154
155 if (rate_limit) {
156 atomic_inc(&key->enabled);
157 schedule_delayed_work(work, rate_limit);
158 } else {
159 jump_label_update(key);
160 }
161 jump_label_unlock();
162}
163
164static void jump_label_update_timeout(struct work_struct *work)
165{
166 struct static_key_deferred *key =
167 container_of(work, struct static_key_deferred, work.work);
168 __static_key_slow_dec(&key->key, 0, NULL);
169}
170
171void static_key_slow_dec(struct static_key *key)
172{
173 STATIC_KEY_CHECK_USE();
174 __static_key_slow_dec(key, 0, NULL);
175}
176EXPORT_SYMBOL_GPL(static_key_slow_dec);
177
178void static_key_slow_dec_deferred(struct static_key_deferred *key)
179{
180 STATIC_KEY_CHECK_USE();
181 __static_key_slow_dec(&key->key, key->timeout, &key->work);
182}
183EXPORT_SYMBOL_GPL(static_key_slow_dec_deferred);
184
185void static_key_deferred_flush(struct static_key_deferred *key)
186{
187 STATIC_KEY_CHECK_USE();
188 flush_delayed_work(&key->work);
189}
190EXPORT_SYMBOL_GPL(static_key_deferred_flush);
191
192void jump_label_rate_limit(struct static_key_deferred *key,
193 unsigned long rl)
194{
195 STATIC_KEY_CHECK_USE();
196 key->timeout = rl;
197 INIT_DELAYED_WORK(&key->work, jump_label_update_timeout);
198}
199EXPORT_SYMBOL_GPL(jump_label_rate_limit);
200
201static int addr_conflict(struct jump_entry *entry, void *start, void *end)
202{
203 if (entry->code <= (unsigned long)end &&
204 entry->code + JUMP_LABEL_NOP_SIZE > (unsigned long)start)
205 return 1;
206
207 return 0;
208}
209
210static int __jump_label_text_reserved(struct jump_entry *iter_start,
211 struct jump_entry *iter_stop, void *start, void *end)
212{
213 struct jump_entry *iter;
214
215 iter = iter_start;
216 while (iter < iter_stop) {
217 if (addr_conflict(iter, start, end))
218 return 1;
219 iter++;
220 }
221
222 return 0;
223}
224
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229
230
231void __weak __init_or_module arch_jump_label_transform_static(struct jump_entry *entry,
232 enum jump_label_type type)
233{
234 arch_jump_label_transform(entry, type);
235}
236
237static inline struct jump_entry *static_key_entries(struct static_key *key)
238{
239 WARN_ON_ONCE(key->type & JUMP_TYPE_LINKED);
240 return (struct jump_entry *)(key->type & ~JUMP_TYPE_MASK);
241}
242
243static inline bool static_key_type(struct static_key *key)
244{
245 return key->type & JUMP_TYPE_TRUE;
246}
247
248static inline bool static_key_linked(struct static_key *key)
249{
250 return key->type & JUMP_TYPE_LINKED;
251}
252
253static inline void static_key_clear_linked(struct static_key *key)
254{
255 key->type &= ~JUMP_TYPE_LINKED;
256}
257
258static inline void static_key_set_linked(struct static_key *key)
259{
260 key->type |= JUMP_TYPE_LINKED;
261}
262
263static inline struct static_key *jump_entry_key(struct jump_entry *entry)
264{
265 return (struct static_key *)((unsigned long)entry->key & ~1UL);
266}
267
268static bool jump_entry_branch(struct jump_entry *entry)
269{
270 return (unsigned long)entry->key & 1UL;
271}
272
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281
282static void static_key_set_entries(struct static_key *key,
283 struct jump_entry *entries)
284{
285 unsigned long type;
286
287 WARN_ON_ONCE((unsigned long)entries & JUMP_TYPE_MASK);
288 type = key->type & JUMP_TYPE_MASK;
289 key->entries = entries;
290 key->type |= type;
291}
292
293static enum jump_label_type jump_label_type(struct jump_entry *entry)
294{
295 struct static_key *key = jump_entry_key(entry);
296 bool enabled = static_key_enabled(key);
297 bool branch = jump_entry_branch(entry);
298
299
300 return enabled ^ branch;
301}
302
303static void __jump_label_update(struct static_key *key,
304 struct jump_entry *entry,
305 struct jump_entry *stop)
306{
307 for (; (entry < stop) && (jump_entry_key(entry) == key); entry++) {
308
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311
312
313 if (entry->code && kernel_text_address(entry->code))
314 arch_jump_label_transform(entry, jump_label_type(entry));
315 }
316}
317
318void __init jump_label_init(void)
319{
320 struct jump_entry *iter_start = __start___jump_table;
321 struct jump_entry *iter_stop = __stop___jump_table;
322 struct static_key *key = NULL;
323 struct jump_entry *iter;
324
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329
330
331 BUILD_BUG_ON((int)ATOMIC_INIT(0) != 0);
332 BUILD_BUG_ON((int)ATOMIC_INIT(1) != 1);
333
334 if (static_key_initialized)
335 return;
336
337 jump_label_lock();
338 jump_label_sort_entries(iter_start, iter_stop);
339
340 for (iter = iter_start; iter < iter_stop; iter++) {
341 struct static_key *iterk;
342
343
344 if (jump_label_type(iter) == JUMP_LABEL_NOP)
345 arch_jump_label_transform_static(iter, JUMP_LABEL_NOP);
346
347 iterk = jump_entry_key(iter);
348 if (iterk == key)
349 continue;
350
351 key = iterk;
352 static_key_set_entries(key, iter);
353 }
354 static_key_initialized = true;
355 jump_label_unlock();
356}
357
358#ifdef CONFIG_MODULES
359
360static enum jump_label_type jump_label_init_type(struct jump_entry *entry)
361{
362 struct static_key *key = jump_entry_key(entry);
363 bool type = static_key_type(key);
364 bool branch = jump_entry_branch(entry);
365
366
367 return type ^ branch;
368}
369
370struct static_key_mod {
371 struct static_key_mod *next;
372 struct jump_entry *entries;
373 struct module *mod;
374};
375
376static inline struct static_key_mod *static_key_mod(struct static_key *key)
377{
378 WARN_ON_ONCE(!(key->type & JUMP_TYPE_LINKED));
379 return (struct static_key_mod *)(key->type & ~JUMP_TYPE_MASK);
380}
381
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386
387
388static void static_key_set_mod(struct static_key *key,
389 struct static_key_mod *mod)
390{
391 unsigned long type;
392
393 WARN_ON_ONCE((unsigned long)mod & JUMP_TYPE_MASK);
394 type = key->type & JUMP_TYPE_MASK;
395 key->next = mod;
396 key->type |= type;
397}
398
399static int __jump_label_mod_text_reserved(void *start, void *end)
400{
401 struct module *mod;
402
403 preempt_disable();
404 mod = __module_text_address((unsigned long)start);
405 WARN_ON_ONCE(__module_text_address((unsigned long)end) != mod);
406 preempt_enable();
407
408 if (!mod)
409 return 0;
410
411
412 return __jump_label_text_reserved(mod->jump_entries,
413 mod->jump_entries + mod->num_jump_entries,
414 start, end);
415}
416
417static void __jump_label_mod_update(struct static_key *key)
418{
419 struct static_key_mod *mod;
420
421 for (mod = static_key_mod(key); mod; mod = mod->next) {
422 struct jump_entry *stop;
423 struct module *m;
424
425
426
427
428
429 if (!mod->entries)
430 continue;
431
432 m = mod->mod;
433 if (!m)
434 stop = __stop___jump_table;
435 else
436 stop = m->jump_entries + m->num_jump_entries;
437 __jump_label_update(key, mod->entries, stop);
438 }
439}
440
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447
448
449void jump_label_apply_nops(struct module *mod)
450{
451 struct jump_entry *iter_start = mod->jump_entries;
452 struct jump_entry *iter_stop = iter_start + mod->num_jump_entries;
453 struct jump_entry *iter;
454
455
456 if (iter_start == iter_stop)
457 return;
458
459 for (iter = iter_start; iter < iter_stop; iter++) {
460
461 if (jump_label_init_type(iter) == JUMP_LABEL_NOP)
462 arch_jump_label_transform_static(iter, JUMP_LABEL_NOP);
463 }
464}
465
466static int jump_label_add_module(struct module *mod)
467{
468 struct jump_entry *iter_start = mod->jump_entries;
469 struct jump_entry *iter_stop = iter_start + mod->num_jump_entries;
470 struct jump_entry *iter;
471 struct static_key *key = NULL;
472 struct static_key_mod *jlm, *jlm2;
473
474
475 if (iter_start == iter_stop)
476 return 0;
477
478 jump_label_sort_entries(iter_start, iter_stop);
479
480 for (iter = iter_start; iter < iter_stop; iter++) {
481 struct static_key *iterk;
482
483 iterk = jump_entry_key(iter);
484 if (iterk == key)
485 continue;
486
487 key = iterk;
488 if (within_module(iter->key, mod)) {
489 static_key_set_entries(key, iter);
490 continue;
491 }
492 jlm = kzalloc(sizeof(struct static_key_mod), GFP_KERNEL);
493 if (!jlm)
494 return -ENOMEM;
495 if (!static_key_linked(key)) {
496 jlm2 = kzalloc(sizeof(struct static_key_mod),
497 GFP_KERNEL);
498 if (!jlm2) {
499 kfree(jlm);
500 return -ENOMEM;
501 }
502 preempt_disable();
503 jlm2->mod = __module_address((unsigned long)key);
504 preempt_enable();
505 jlm2->entries = static_key_entries(key);
506 jlm2->next = NULL;
507 static_key_set_mod(key, jlm2);
508 static_key_set_linked(key);
509 }
510 jlm->mod = mod;
511 jlm->entries = iter;
512 jlm->next = static_key_mod(key);
513 static_key_set_mod(key, jlm);
514 static_key_set_linked(key);
515
516
517 if (jump_label_type(iter) != jump_label_init_type(iter))
518 __jump_label_update(key, iter, iter_stop);
519 }
520
521 return 0;
522}
523
524static void jump_label_del_module(struct module *mod)
525{
526 struct jump_entry *iter_start = mod->jump_entries;
527 struct jump_entry *iter_stop = iter_start + mod->num_jump_entries;
528 struct jump_entry *iter;
529 struct static_key *key = NULL;
530 struct static_key_mod *jlm, **prev;
531
532 for (iter = iter_start; iter < iter_stop; iter++) {
533 if (jump_entry_key(iter) == key)
534 continue;
535
536 key = jump_entry_key(iter);
537
538 if (within_module(iter->key, mod))
539 continue;
540
541
542 if (WARN_ON(!static_key_linked(key)))
543 continue;
544
545 prev = &key->next;
546 jlm = static_key_mod(key);
547
548 while (jlm && jlm->mod != mod) {
549 prev = &jlm->next;
550 jlm = jlm->next;
551 }
552
553
554 if (WARN_ON(!jlm))
555 continue;
556
557 if (prev == &key->next)
558 static_key_set_mod(key, jlm->next);
559 else
560 *prev = jlm->next;
561
562 kfree(jlm);
563
564 jlm = static_key_mod(key);
565
566 if (jlm->next == NULL) {
567 static_key_set_entries(key, jlm->entries);
568 static_key_clear_linked(key);
569 kfree(jlm);
570 }
571 }
572}
573
574static void jump_label_invalidate_module_init(struct module *mod)
575{
576 struct jump_entry *iter_start = mod->jump_entries;
577 struct jump_entry *iter_stop = iter_start + mod->num_jump_entries;
578 struct jump_entry *iter;
579
580 for (iter = iter_start; iter < iter_stop; iter++) {
581 if (within_module_init(iter->code, mod))
582 iter->code = 0;
583 }
584}
585
586static int
587jump_label_module_notify(struct notifier_block *self, unsigned long val,
588 void *data)
589{
590 struct module *mod = data;
591 int ret = 0;
592
593 switch (val) {
594 case MODULE_STATE_COMING:
595 jump_label_lock();
596 ret = jump_label_add_module(mod);
597 if (ret) {
598 WARN(1, "Failed to allocatote memory: jump_label may not work properly.\n");
599 jump_label_del_module(mod);
600 }
601 jump_label_unlock();
602 break;
603 case MODULE_STATE_GOING:
604 jump_label_lock();
605 jump_label_del_module(mod);
606 jump_label_unlock();
607 break;
608 case MODULE_STATE_LIVE:
609 jump_label_lock();
610 jump_label_invalidate_module_init(mod);
611 jump_label_unlock();
612 break;
613 }
614
615 return notifier_from_errno(ret);
616}
617
618static struct notifier_block jump_label_module_nb = {
619 .notifier_call = jump_label_module_notify,
620 .priority = 1,
621};
622
623static __init int jump_label_init_module(void)
624{
625 return register_module_notifier(&jump_label_module_nb);
626}
627early_initcall(jump_label_init_module);
628
629#endif
630
631
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642
643
644int jump_label_text_reserved(void *start, void *end)
645{
646 int ret = __jump_label_text_reserved(__start___jump_table,
647 __stop___jump_table, start, end);
648
649 if (ret)
650 return ret;
651
652#ifdef CONFIG_MODULES
653 ret = __jump_label_mod_text_reserved(start, end);
654#endif
655 return ret;
656}
657
658static void jump_label_update(struct static_key *key)
659{
660 struct jump_entry *stop = __stop___jump_table;
661 struct jump_entry *entry;
662#ifdef CONFIG_MODULES
663 struct module *mod;
664
665 if (static_key_linked(key)) {
666 __jump_label_mod_update(key);
667 return;
668 }
669
670 preempt_disable();
671 mod = __module_address((unsigned long)key);
672 if (mod)
673 stop = mod->jump_entries + mod->num_jump_entries;
674 preempt_enable();
675#endif
676 entry = static_key_entries(key);
677
678 if (entry)
679 __jump_label_update(key, entry, stop);
680}
681
682#ifdef CONFIG_STATIC_KEYS_SELFTEST
683static DEFINE_STATIC_KEY_TRUE(sk_true);
684static DEFINE_STATIC_KEY_FALSE(sk_false);
685
686static __init int jump_label_test(void)
687{
688 int i;
689
690 for (i = 0; i < 2; i++) {
691 WARN_ON(static_key_enabled(&sk_true.key) != true);
692 WARN_ON(static_key_enabled(&sk_false.key) != false);
693
694 WARN_ON(!static_branch_likely(&sk_true));
695 WARN_ON(!static_branch_unlikely(&sk_true));
696 WARN_ON(static_branch_likely(&sk_false));
697 WARN_ON(static_branch_unlikely(&sk_false));
698
699 static_branch_disable(&sk_true);
700 static_branch_enable(&sk_false);
701
702 WARN_ON(static_key_enabled(&sk_true.key) == true);
703 WARN_ON(static_key_enabled(&sk_false.key) == false);
704
705 WARN_ON(static_branch_likely(&sk_true));
706 WARN_ON(static_branch_unlikely(&sk_true));
707 WARN_ON(!static_branch_likely(&sk_false));
708 WARN_ON(!static_branch_unlikely(&sk_false));
709
710 static_branch_enable(&sk_true);
711 static_branch_disable(&sk_false);
712 }
713
714 return 0;
715}
716late_initcall(jump_label_test);
717#endif
718
719#endif
720